Project report in gail(india) limited prakash

ANALYSIS OF PROPANE REFRIGERATION UNIT

AND STUDY OF NAPHTHA LOSSES AT LOADING

GANTRY

Vijaipur, Guna (M.P)

Mr. Vinay Patni, Prakash Chand Baliwal,

Sr. Manager (GPU-OPS) Institute Of Technology, Guru

Ghasidas(Central) University,Bilaspur

2 | Analysis Of Propane Refrigeration Unit And Study Of Naphtha Losses At Loading Gantry

Certificate

This is to certify that PRAKASH CHAND BALIWAL student of B.Tech in Chemical

Engineering at INSTITUTE OF TECHNOLOGY, GURU GHASIDAS(CENTRAL)

UNIVERSITY, BILASPUR, has successfully completed training in Gas Processing

Unit(GPU),Department at GAIL (India) Limited, Vijaipur from 20th June to 21th July.

He has successfully completed the project entitled, “ANALYSIS OF PROPANE

REFRIGERATION UNIT AND STUDY OF NAPHTHA LOSSES AT LOADING GANTRY”

under the guidance of Mr. K.V.S. Rao, DGM (GPU-OPS) and Mr. Vinay Patni, Sr.

Manager, (GPU-OPS), GAIL (India) Ltd.

His conduct and behavior during the Vocational training period was found to be

exemplary.

Mr. K. V. S Rao, Mr. Vinay Patni,

DGM (GPU-OPS), Sr. Manager, (GPU - OPS)

GAIL (India) Ltd. GAIL (India) Ltd.


Abstract

The following report describes an overview of the outcomes of work undertaken

by me during the industrial training in GAIL (India), Vijaipur. During this training the

LPG extraction process from natural gas, taking place in this plant was studied. All

the modules constituting the plant including the offsite were visited and the

operation involved was learnt from the plant officials. The placement of equipment

and utilities were analyzed in terms of feasibility and economics. The usage and

working of different type of valves and pumps at specific locations were also learnt.

Training at Fire & Safety department was given, where we were introduced with all

Do’s and Don’ts.

A project based of calculation of the tons of refrigeration of both the phases of the

plant which consisted of heat rejected/absorbed by evaporators and condensers

and the work done by compressors. I also undertook the study of naphtha leakage

at the loading gantry in which I plotted a Temperature v/s Losses curve to indicate

the feasible atmospheric conditions to minimize the losses.


Acknowledgement

No work can be completed successfully unless the path of wisdom is illuminated by

the luminous and excellent guidance. Dozens of persons have aided by devoting

their help in preparing this project report.

I would like to express my gratitude to all those who gave me the possibility to

complete this project work. I want to thank the Department of Chemical

engineering, of my institution for giving me the permission to commence this

project in the first instance.

I am deeply indebted to my guide Mr. K.V.S. Rao (DGM, GPU-OPS) and Mr. Vinay

Patni (Senior Manager, GPU-OPS), GAIL (India) Ltd, Vijaipur, whose help,

stimulating suggestions and encouragement helped me in all the time of our

project work.

Also, I extend my sincere thanks to Mr. Lovejit Singh and Mr. Hara Gopal Gadi for

their constant interaction, help, valuable suggestions and support during my

project period.


Index

Title Page No.

Chapter -1 Introduction

About GAIL

GAIL's Business Portfolio

GAIL, Vijaipur Plant

Process Description

Offsites

6

Chapter – 2 Overview of Project

Refrigeration

Tons of Refrigeration

Propane Refrigeration Unit

Naphtha

Naphtha Loading

20

Chapter – 3 Calculations

27

Chapter – 4 Results and Discussions

36

Chapter – 5 Conclusion

39

References 40 List of Tables 41 List of Figures 42 List of Photographs 43


Chapter - 1

Introduction

1.1 About GAIL:

GAIL (India) Limited, is India's flagship Natural Gas company, integrating all aspects

of the Natural Gas value chain including Exploration & Production, Processing,

Transmission, Distribution and Marketing and its related services. Now it is

spearheading the move to a new era of clean fuel industrialisation, creating a

quadrilateral of green energy corridors that connect major consumption centres in

India with major gas fields, LNG terminals and other cross border gas sourcing

points.

1.2 GAIL's Business Portfolio includes:

7,700 km of Natural Gas high pressure trunk pipeline with a capacity to carry

157 MMSCMD of natural gas across the country

7 LPG Gas Processing Units to produce 1.2 MMTPA of LPG and other liquid

hydrocarbons

North India's only gas based integrated Petrochemical complex at Pata with

a capacity of producing 4,10,000 TPA of Polymers

1,922 km of LPG Transmission pipeline network with a capacity to transport

3.8 MMTPA of LPG

27 oil and gas Exploration blocks and 3 Coal Bed Methane Blocks

13,000 km of OFC network offering highly dependable band with for telecom

service providers

Joint venture companies in Delhi, Mumbai, Hyderabad, Kanpur, Agra,

Lucknow, Bhopal, Agartala and Pune, for supplying Piped Natural Gas (PNG)

to households and commercial users, and Compressed Natural Gas (CNG) to

the transport sector


IPCL o

HAZIRA

VIJAIPUR

VAGHODIA

o JALALPURA

o SANDWATA

KASARBADI o

JHABUADUDHMAL o

DEVGARHBARIA o

o SHERPURALPG PLANT

o VEMARJHAGADIYA oo SAMNI

KHERA

MOHANKOT o

o JAMBUDI

o KACHACHIBARODA

JAGOTI o

GORKHPURA o

JAISINGHPURA o

DHATARWADA o

MANAGEMENT CONTROL CENTRE LPG PLANT

DESU

AURAIYA

SONIPAT SIWALI

BAHADURGARH

G’ BAD

DADRI

oKARANPUR

BAJHERA o

o FARIDABAD

o NAWADIA

GURGAON o

SHAHJAHANPUR oo PIPRAULA

oS

AC

HE

ND

I

o MATHURA

SCHEMATIC DIAGRAM OF HVJ/GREP/DV PIPELINE

AGRA CGS

FIROZABAD

DAHEJ

MAKARWAN o

ANTA o

CHHABRA o

ATTRU o

o BORERI

o CFCL G’PAN

SAMACORE

o BAJRANGGARHo NAISARAI

o KAMAD

o PIRONTH

o KHERI

o BHAUNTI

DUNGARWAHA o

o CHITARAMIANPUR o

o KHARAUWA

o GORABHUPKA

oA

CH

AL

GA

NJ

oM

AU

RW

AN

oT

HU

LE

ND

I

JE

TH

WA

DA

o

LPG PLANT

NTPC

INDOGULF

o JAGDISHPUR

o PHULPUR

IFFCO

NA

RA

YA

NP

UR

o

o MALAKPUR

JIGNIS o

BANDHMAU o

CHAINSA o

o BABRALATCL

o MUNDER

KSFL

o AONLA

IFFCO

NTPC

IOCL

SKBAD

o KHORDAR

o BURDHA

o MARA

o SONE KA GURJA

BAMNIKALAN o

o SIHANA

o JATAULI

SBAD

o S’WASA

MARUTI

IGL

NTPC

NTPC

UPPC PATA

HVJ P/L

DV P/L

GREP P/L

COMP. STN.

LPG PLANT

RR/IP/SV STN.

CONSUMERS

LEGEND

NGMC

NOIDA

KOSAMBA o

o ANKOT

VAGHODIA o

o

o MALANPUR

KELARAS o o GWALIOR

o

KMPL 12”x 72 KMS

NFL o

CONSUMERS

SFCL KOTA

VKPL (18’’X140 KMS.)

o IBRAHIMPUR

DHAULPUR oIDPL 10”x33 KMS

RRVNL

DEWAS

PITHAMPUR

JIPPL 16”x 92 KMS

o INDORE12”x 32 KMS


Participating stake in the Dahej LNG Terminal and the upcoming Kochi LNG

Terminal in Kerala

GAIL has been entrusted with the responsibility of reviving the LNG terminal

at Dabhol as well as sourcing LNG

GAIL Gas Limited, a wholly owned subsidiary of GAIL (India) Limited, was

incorporated on May 27, 2008 for the smooth implementation of City Gas

Distribution (CGD) projects. GAIL Gas Limited is a limited company under the

Companies Act, 1956

Established presence in the CNG and City Gas sectors in Egypt through equity

participation in three Egyptian companies: Fayum Gas Company SAE, Shell

CNG SAE and National Gas Company SAE

Stake in China Gas Holding to explore opportunities in the CNG sector in

mainland China

A wholly-owned subsidiary company GAIL Global (Singapore) Pte Ltd in

Singapore

1.3 GAIL, Vijaipur Plant:


Fig 1.1 Layout of Gas Processing Unit (GPU)

Gail have its first LPG plant at Vijaipur .In this plant LPG is extracted from natural

gas by following latest Turbo expander process .The design gas processing capacity

of the plant is 15 million standard cubic meters of gas per day (mmscmd) with

annual LPG production capacity being 4,06,000 million tons. The other products

that are recovered in the process are propane, pentane and naphtha

Commissioning Dates

LPG train-11 (phase-I) - Feb 11, 1991

LPG train -12 (phase-II) - Feb 11,1992

Steps Involved

Gas receiving ,drying and regeneration

Pre-cooling and chill down in expander

Distillation

1.4 Process Description:

LPG recovery facility of each plant is designed to handle 7.5 mmscmd of gas. The

natural gas is received from HVJ pipeline to recover LPG, propane, pentane and

SBPS (Special Boiling Point Spirit). Feed gas from HVJ pipeline compressor station

is presently available at 53.5 kg/cm2 abs at temperature of 31 oC.

Gas Receiving ,Drying And Regeneration

The natural gas coming from HVJ pipeline flows through a knock out

drum (KOD), where the liquid present in gas is knocked off


From the knock out drum it goes to drier (one operating + one

regeneration) having molecular sieve (Zeolite, size 4A) where the

moisture content reduces from 81 kg/mmscmd to1 kg/mmscmd


Fig 1.2 Process Flow Diagram TR-12


Pre Cooling And Chill Down In Expander

This dried gas is then passed through the feed gas chiller (based on

Linde’s principle) and where the temperature of gas reduce to -39oC and

some amount of gas converted to liquid or condensate

The partially condensate gas is then passed through the separator 1

where the gas and the condensate are separated

As the whole amount of gas is not condensate so it is required to reduce

the temperature of gas further lower than -39oC. The gas from the

separator 1 is fed to expander-compressor where the gases are allowed

to expand isentropically (adiabatically and reversibly) as result of

expansion process heat is released and temperature further reduced

from -39 oC to -70 o C

Distillation

LEF COLUMN

The condensate liquid is then separated in separator 2 and the liquid and

gas from separator 2 is first used as cooling media in the chiller and the

liquid is fed to LEF (light end fractionation column) and the gas is used to

provide cooling in the LEF column condenser

The light hydro carbon (CH4) and CO2, N2 are separated as the top product

in LEF column and the remaining hydrocarbon are taken as bottom

product

PROPANE COLUMN

The bottom product hydrocarbon is then fed to propane column (Sieve

or valve tray column) where propane is recovered as the top product

and sent to propane storage tanks


GAS COMPRESSOR STATION CENTRALLIZED PIPELINE MAINT. BASE

LPG PHASE 1(TRAIN 11) LPG PHASE 2 (TRAIN 12)


LPG COLUMN

The bottom product from the propane column is fed to LPG column

which is packed bed column, and packing material used is of pall rings.

When the LPG (50:50) by wt. of propane and butane are recovered as the

top product and the bottom product is called natural gasoline (NGL)

SBPS COLUMN

The NGL from LPG column is fed to SBPS column where pentane is

separated as product and SBPS is extracted as bottom product

The LEF O/H gases are heated in regeneration gas heater and used for

regeneration of drier. The gases used as regeneration and remaining LEF

O/H gases are called lean gases and are sent to HVJ after compressing as

HP gas at 56 Kg/cm2 and MP gas at 46 Kg/cm2

1.5 Offsite:

The central utilities of factory consist of following:

Raw water, Service Water, Fire Water, Cooling Water, Drinking Water

Water is required to meet the cooling water makeup, service

water and drinking water requirements. The raw water system

consists of a raw water reservoir, raw water treatment plant and

filtered water reservoir. This raw is stored in two raw water reservoir

having a capacity of 62500 m3.


Service water is supplied to LPG unit from offsite area at a

pressure of 7.5 kg/cm2a through a 2” header. Service water is made

available at various hose stations.

Compressed air system

A 3” instrument air header supplies instrument air to the unit at

a pressure of 7.5 kg/cm2a. A block valve with a blind is provided at the

battery limit. A pressure gauge indicates the pressure of instrument

air to the unit. The various instrument air tapping are taken off this

header. The header is provided with a low pressure alarm. Maximum

requirement of Instrument Air is estimated at 400 NM3/hr for LPG unit

with offsite. Plant air is supplied to the unit at various hose stations

through a 2” header at a pressure of 7.0 kg/cm2a.

Inert gas system

Inert gas is supplied to the unit at a pressure of 9.0 kg/cm2a.

Inert gas is produced by combustion of fuel gas in an inert gas

generator. This is coupled with a drying unit in the offsites. Inert gas

of the following specifications shall be supplied to the plant.

i) Dew Point @ 9.0 kg/cm2a, °C : -40

ii) Temperature at B/L,°C, Nor : 40 °C

iii) Composition


Component Volume, %

H2 0.1 (max.)

O2 0.5 (max.)

CO 0.1 (max.)

CO2& N2 Balance

Oil content Oil free

Inert gas is made available at the various hose stations and for

blanketing of V-108 (Hot Water Expansion Vessel). It is also used for

purging of distance piece of reciprocating compressors.

Steam and soft water system

Soft water is used in the LPG Unit for hot water system make

up, Residue Gas Compressor jacket cooling make up. The soft water is

supplied from offsite through a 2” line at a pressure of 9.5 kg/cm2a.

Soft water header is provided with a flow indicator. Pressure gauge is

also provided on the header.

Product storage and transfer

LPG form LPG recovery plant is received via 6’’ Pipeline and

stored in the LPG spheres. The spheres are of nominal capacity 2200m3

each. Normal storage pressure is 10.5 kg/cm2corresponding to a

temperature of 450C. The spheres are insulated for fire protection and


are also provided with spray water connection in order to keep the

surface cool in case of fire in the adjoining area.

Following facilities exist for storage of the products:

(a) LPG - Eight Spheres of 2575 M3 water capacity

each

(b) Propane - Three Spheres of 2575 M3 water capacity each

(c) Pentane - Five Bullets of 198 M3 water capacity each

(d) NAPHTHA - Two Tanks of 1300 M3 water capacity each

Product loading and dispatch system

Following facilities exist for loading & dispatch of the products

A loading control room monitors and records all the loading

operations which are taking place at rail and road gentries. This control

room is also provided with fire and safety panels where all the

indications from gas detectors located around the loading are

monitored:

(a) LPG - (i) Rail Loading Gantry with Eighty loading points

(ii) Road Loading Gantry with Eight loading bays

(b) Propane - Road Loading Gantry with Four loading bays

(c) Pentane - Road Loading Gantry with Two loading bays

(d) NAPHTHA - Road Loading Gantry with Three loading bays

Chemical storage and distribution

The chemical used in LPG recovery unit is Methanol. Methanol

is used as antifreeze agent whenever ice or hydrate formation is likely

to take place. Methanol requirement arises mainly during plant


startup and during times when there is ingress of moisture into the

system. Methanol dissolves ice/hydrate and comes out of the system

along with the heavies.

Methanol from offsite storage is received in the methanol pot.

Methanol pot is 2.2 m OD and 4.4 m height vertical vessel of carbon

steel construction. The vessel is blanketed with inert gas at a pressure

of 1.05 kg/cm2a through pressure regulator and discharge pressure of

61 kg/cm2a. The vessel is provided with a pressure cum vacuum relief

valve. For safety against high pressure 2” rupture disc is provided.

Methanol from the condensate pot is pumped to the methanol supply

header of LPG plant by methanol injection pumps. Methanol from the

supply header is injected at various locations throughout the unit,

whenever it is required.

Flare system

The discharge from various safety valves, control valves and

pump casing vents in the unit are collected in the 24” flare header

which flows to flare K.O. drum with a slope of 1:500. The normal

operating pressure is 1.5 kg/cm2a but this may go to 4.5 kg/cm2a

during peak flaring. Flare K.O. drum is 3.2 m OD and about 12 m long

horizontal vessel of carbon steel construction. Flare gases from K.O.

drum outlet are routed through a 30” line to 30” flare header for the

LPG plant. Flare K.O. Drum is provided with a high level alarm. Flare

header is provided with a fuel gas purge connection at the dead end


of the header in LPG Unit. The 12” header is provided with a fuel gas

purge connection at the dead ends of the header in Propane area. The

flow of fuel gas is regulated by restriction orifice. Excessive flaring of

hot gases is to be followed by higher purge rates of fuel gas to avoid

flare header developing vacuum. High fuel gas purge rates are

obtained through HCV, which is used after high flaring.

Effluent Water treatment system

The effluent treatment plant attached to the LPG Recovery

Plant is designed to receive and treat four types of effluents generated

from the phase-I and phase-II plants. During the treatment process

two main types of byproducts are generated from all effluents, viz slop

oil and sludge which are collected in separate circuits and disposed off

to the assigned areas. The treated and filtered water devoid of

suspended solids, oil, BOD etc. is collected and stored in guard ponds.

From these ponds treated water is released after monitoring the

effluent quality conforming to the standards.


Chapter – 2

Overview of the Project

2.1 Refrigeration:

The transfer of heat from a low-temperature region to a high-temperature one

requires special devices called refrigerators. Refrigerators are cyclic devices, and

the working fluids used in the refrigeration cycles are called refrigerants. A

refrigerator is shown schematically in Fig. 2.1. Here QL is the magnitude of the heat

removed from the refrigerated space at temperature TL, QH is the magnitude of the

heat rejected to the warm space at temperature TH, and Wnet, in is the net work

input to the refrigerator.

Fig 2.1 A schematic refrigerator

Warm

Environment

Cold Refrigerated

Space

W net, in

R

QH

QL


2.2 Tons of refrigeration:

The capacity of a refrigeration system that can freeze 1 ton (2000 lbm) of liquid

water at 0°C (32°F) into ice at 0°C in 24 h is said to be 1 ton. One ton of

refrigeration is equivalent to 211 kJ/min or 200 Btu/min. The cooling load of a

typical 200-m2 residence is in the 3-ton (10-kW) range.

2.3 Propane Refrigeration Unit:

Fig 2.2 Schematic of Propane Refrigeration Unit


The above system is a refigeration cycle comprising of three main components

viz. Evaporator, Condensor and Compressor.

The nomenclature of the vessels are as follows-

1. V -123 Propane Refrigerant Accumulator

2. V-124 Propane I-Stage Suction K.0. Drum

3. V-125 Propane II Stage Suction K.O. Drum

4. V-126 Propane Refrigerant Flash Pot

5. E-125 Propane Condenser

6. E-126 LEF Condenser-2

Propane refrigeration system has been provided to supply refrigeration in LEF

condenser of LEF column and feed gas chiller in combination recovery mode of

operation, this system operate in close cycle with, make-up, two stage refrigeration

system is provided. The 1st stage of system is at 1.2kg/cm2 pressure and -37.6 0C

temperature. The 2nd stage is at 4.41 kg/cm2 a pressure and -2.29 0C temperature.

The second state is economizer stage with no process load and is meant to reduce

energy consumption of the system

Propane being compressed by Propane refrigeration compressor is condensed in

Propane condenser and taken to accumulator. Form accumulator the refrigerant

is taken to 2nd stage suction K.O. drum where it is flashed. Vapor from this drum

are taken to 2nd stage compressor suction where they are mixed with 1st stage

discharge vapors. Liquid from 2nd stage suction K.O. drum are taken to LEF

condenser-2 and cold box to supply refrigeration duty.

Vapors generated in heat exchangers are taken to 1st stage suction K.O drum,

vapors from V-124 go to the 1st stage compressor suction. The compressor is

centrifugal type by gas turbine and is suitable to handle either propane or

propylene refrigerant.

It should be noted that propylene refrigerant shall not be available since PP/PDH

project execution has been deferred by GAIL. Hence propane instead of propylene

refrigerant shall be used as refrigerant for combination recovery mode of operation

in the LPG plant.

2.4 Naptha:


Naphtha is a liquid petroleum product that boils from about 30°C (86°F) to approximately 200°C (392°F), although there are different grades of naphtha within this extensive boiling range that have different boiling ranges. The term petroleum solvent is often used synonymously with naphtha. On a chemical basis, naphtha is difficult to define precisely because it can contain varying amounts of its constituents (paraffins, naphthenes, aromatics, and olefins) in different proportions, in addition to the potential isomers of the paraffins that exist in the naphtha boiling range (Tables 2.1). Naphtha is also represented as having a boiling range and carbon number similar to those of gasoline, being a precursor to gasoline. The so-called petroleum ether solvents are specific-boiling-range naphtha as is ligroin. Thus the term petroleum solvent describes special liquid hydrocarbon fractions obtained from naphtha and used in industrial processes and formulations.

Product Lower Carbon limit

UPPER Carbon limit

Lower Boiling Point (in oC)

Upper Boiling Point (in oC)

Refinary Gas C1 C4 -161 -1 Liquefied petroleum gas

C3 C4 -42 -1

Naphtha C5 C17 36 302 Gasoline C4 C12 -1 216 Kerosene/diesel fuel

C8 C18 126 258

Aviation turbine fuel

C8 C16 126 287

Fuel oil C12 >C20 216 421 Lubricating oil >C20 >343 Wax C17 >C20 302 >343 Asphalt >C20 >343 Coke >C50 >1000

Table 2.1 General Summary of Product Types and Distillation Range

Hazards Identification:

Emergency Overview


Regulatory status : This material is considered hazardous by the

Occupational Safety and Health Administration (OSHA) Hazard

Communication Standard (29 CFR 1910.1200

Hazard Summary : Extremely flammable. Irritating to eyes and

respiratory system. Affects central nervous system. Harmful or fatal if

swallowed. Aspiration Hazard.

Potential Health Effects

Eyes : High vapor concentration or contact may cause irritation and

discomfort.

Skin : Brief contact may cause slight irritation. Skin irritation leading to

dermatitis may occur upon prolonged or repeated contact. Can be

absorbed through skin.

Ingestion : Aspiration hazard if liquid is inhaled into lungs, particularly

from vomiting after ingestion. Aspiration may result in chemical

pneumonia, severe lung damage, respiratory failure and even death.

Inhalation : Vapors or mists from this material can irritate the nose,

throat, and lungs, and can cause signs and symptoms of central

nervous system depression, depending on the concentration and

duration of exposure. Inhalation of high concentrations may cause

central nervous system depression such as dizziness drowsiness,

headache, and similar narcotic symptoms, but no long-term effects

Chronic Exposure : Long-term exposure may cause effects to specific

organs, such as to the liver, kidneys, blood, nervous system, and skin.

Contains benzene, which can cause blood disease, including anemia

and leukemia.

Handling And Storage

Handling : Keep away from fire, sparks and heated surfaces. No

smoking near areas where material is stored or handled. The product

should only be stored and handled in areas with intrinsically safe

electrical classification.


Advice on protection against fire and explosion : Hydrocarbon liquids

including this product can act as a non-conductive flammable liquid (or

static accumulators), and may form ignitable vapor-air mixtures in

storage tanks or other containers. Precautions to prevent static-

initated fire or explosion during transfer, storage or handling, include

but are not limited to these examples:

(1) Ground and bond containers during product transfers. Grounding

and bonding may not be adequate protection to prevent ignition or

explosion of hydrocarbon liquids and vapors that are static

accumulators.

(2) Special slow load procedures for "switch loading" must be followed

to avoid the static ignition hazard that can exist when higher flash

point material (such as fuel oil or diesel) is loaded into tanks previously

containing low flash point products (such gasoline or naphtha).

(3) Storage tank level floats must be effectively bonded.

For more information on precautions to prevent static-initated fire or

explosion, see NFPA 77, Recommended Practice on Static Electricity

(2007), and API Recommended Practice 2003, Protection Against

Ignitions Arising Out of Static, Lightning, and Stray Currents (2008).

Requirements for storage areas and containers : Keep away from

flame, sparks, excessive temperatures and open flame. Use approved

containers. Keep containers closed and clearly labeled. Empty or

partially full product containers or vessels may contain explosive

vapors. Do not pressurize, cut, heat, weld or expose containers to

sources of ignition. Store in a well-ventilated area. The storage area

should comply with NFPA 30 "Flammable and Combustible Liquid

Code". The cleaning of tanks previously containing this product should

follow API Recommended Practice (RP) 2013 "Cleaning Mobile Tanks

In Flammable and Combustible Liquid Service" and API RP 2015

"Cleaning Petroleum Storage Tanks".


Advice on common storage : Keep away from food, drink and animal

feed. Incompatible with oxidizing agents. Incompatible with acids.

2.5 Loading of Naphtha at Gantry

Naphtha loading procedure is given below. 1. Oil company is not involved

2. Naphtha tanker to be checked by opening of bottom valve before weighing for ensuring presence of water/liquid inside the tanker

3. There is only liquid arm connection 4. Check operation of common lever for shutting of outlet valves of individual

chambers 5. Check for calibration/dip for each compartment 6. Check for breathers for lining up 7. Open all the chambers 8. Place liquid arm into one of the chambers from top 9. Loading is done chamber by chamber 10. Level of liquid is monitored by dip rod 11. Apply paste on dip rod to know the level 12. In case of over filling of tanker, unloading is done in an underground tank in the

gantry with the help of hose connection with tanker by gravity 13. Unloaded naphtha is transferred to naphtha storage tank intermittently by

submersible pump through naphtha supply header


Chapter –3

Calculations

For Phase- II (TRAIN - 12)

o E-125 Condensor Heat Rejection

Given Data-

Ti=89.9 oC = 363 K

To=35 oC = 308 K

Volumetric flow rate = 36.3 km3/hr = 10.083 m3/sec

m= 111.83 kmol/sec

R= 8314 J/kmol – K

For calculation of Cp constants used-

A= 1.213

B= 28.785 * 10-3

C= -8.824 * 10-6

Using-

Q = m Cp dT - (i)

Cp = A + BT + CT2

Integrating eq-(i) between limits Ti and To

Q = 504968.515 J = 144 tons

Calculations for tons of refrigeration

for Propane Refrigeration Unit (P.R.U)


o Work done by Compressor

Ist Stage Compressor-

Given Data:

P1= 1.171 kg/cm2=114737.805 Pa

P2= 4.3 kg/cm2

V1= 15.4 km3/hr = 4.27 m3/sec (at N.T.P)

= 3.086 m3/hr (at operating conditons)

k = 1.4

Using-

Compression Ratio (Pc) = P2/P1 = 3.67

=568186.24 W = 568.15 kW

IInd Stage Compressor-

Given Data:

P1= 4.27 kg/cm2=418749.955 Pa

P2= 16.2 kg/cm2

V1= 36.3 km3/hr =10.083 m3/sec (at N.T.P)

V1= 2.39 (at operating conditions)

k=1.4

Compression Ratio (Pc) = P2/P1 = 3.794

k

k -1 P

1 V

1 ( P

c ( k-1 / k)

- 1 ) P =

1.4

1.4 - 1 11473.805* 3.086 * (3.67

(1.4-1/1.4) - 1 ) P =

1.4

1.4 -1 418749.955* 2.39* (3.794

(1.4-1/1.4) - 1 )

P =


= 1807608.54 W = 1807.60 kW

Hence, the total power consumed in a compressor-

Pt = 2.375 MW = 677 tons

o E-126 Heat Rejection

We can calculate the heat lost by estimation of the heat loss at LEF column. Since,

heat taken by the propane in E-126 is heat rejected by vapors of the LEF column.

The flow rate of the vapors has been calculated using general stoichiometry as

indicated below in the figure.

Fig 3.1 LEF Columnn

Given Data-

Ti= -18 oC = 255 K

To= -28 oC = 245 K

(180.3 + 74) m3/hr

54 kg/sec

92.1 m3/hr


m= 54 kg/sec = 2.42 kmol/sec

R= 8.314 KJ/kmol – K

Using-

Q = m Cp dT - (i)

Cp = A + BT + CT2

Integrating eq-(i) between limits Ti and To

Gases Mole Fraction

A B * 10-3 C * 10-6 Mole fraction x Cp x T (in kJ/kmol)

C1 0.65 1.702 9.081 -2.164 237.45 C2 0.25 1.131 19.225 -5.561 140.17 C3 0.02 1.213 28.785 -8.824 15.76

CO2 0.08 5.457 1.045 - 45.65 Total 1017.98

Table 3.1 – Calulation of Cp from the constants for PHASE - II

Q = 2465.06 kW = 703 tons

o V-126 flash pot Heat Rejection

Valve LIC-305 is closed. Hence, no there is no flow of propane towards V-126. So,

there is no heat rejection.

Q = 0

For Phase- I (TRAIN - 11)

o E-125 Condensor Heat Rejection


Similar to the calculations of the Phase-II

Q = 456.37 kJ = 130 ton

o V-126 flash pot Heat Rejection

Fig 3.2 : The Basic Representation Of Chiller

The stream is used for maintaing the temperature inside the chiller stream.

So, the heat given by it equilvalent to heat taken by the chiller.

Latent heat of vaporization of propane at 298 K, L = 81.76 cal/gm

ΔHT2 = ΔHT1 (1-Tr2 ).38

(1-Tr1).38

where Tr is reduced temp.

At T =228.7 k, ΔHvap. = 105.689 cal/gm = 442.41 kJ/kg

Tin = Tout = 228.7 K


Only phase change takes place, no use of sensible heat of propane

Now, propane entering chiller = 14895.55 kg /hr = 4.14 kg/sec

L= 415.85 kJ/kg

Heat lost by the stream =m*L

Therefore,

Q = 1721.94 kW= 491 ton

o E-126 Heat Rejection

Similar to the calculations of the Phase-II

Ti= -9 oC = 264 K

To= -35 oC = 238 K

m= 54 kg/sec = 2.42 kmol/sec

Gases

Mole Fraction

A B * 10-3 C * 10-6 Mole fraction x Cp x T (in kJ/kmol)

C1 0.65 1.702 9.081 -2.164 536.95 C2 0.25 1.131 19.225 -5.561 314.5 C3 0.02 1.213 28.785 -8.824 33.22

CO2 0.08 5.457 1.045 - 98.90 Total 983.57

Table 3.2 – Calulation of Cp from the constants for PHASE - I

Q = 2380.24 kW = 679 tons


The table shows the average losses of the naphtha during various periods of the

year.

Period w.e.f 2013-2014 Losses (in metric tons per month)

April 74 May 27 June 63 July 29

August 5 September 26

October 50 November 8 December 19

January 24 February 20

March 24

Table 3.3 – Losses in MT per month

There are many components of Naphtha as discussed earlier. So it is very complex

to analyze their respective vapor pressures and partial pressures. Hence, we have

focused on the major components and all the calculations have been performed

neglecting of the minor components.

Sr. No.

Component Composition in mole %

Ps at 30 oC (kPa)

Ps at 35 oC (kPa)

Ps at 40 oC (kPa)

Ps at 45 oC (kPa)

Ps at 50 oC (kPa)

1. Iso– pentane 15 138.295

163.27

191.62

223.60

259.53

2 Pentane 25 81.63 97.26 115.15

135.50

158.33

Estimation of Losses of Naphtha at

Loading Gantry


3. 2,3-dimethylbutan

e

2 37.93 45.98 55.12 65.76 77.96

4. 2-dimethylpenta

ne

9 30.8 41.06 51.33 61.61 77.01

5. 3-methylpentane

4 30.8 41.06 51.33 61.61 77.01

6. Hexane 10 24.75 30.35 36.94 44.62 53.51

7. 2,2-dimethylpenta

ne

5 34.35 41.77 50.4 60.4 71.9

8. Benzene 5 15.4 16.7 24.3 29.74 36.33

9. Cyclohexane 7 16.33 20.16 24.72 30.07 36.33

10. 2-methylhexane

2 12.55 15.4 18.48 22.49 28.75

11. Heptane 3 7.69 9.74 12.22 15.12 18.72 12. Methyl

cyclohexane 5 7.73 9.72 12.11 14.97 18.34

13. Toluene 3 4.86 6.2 7.85 9.84 12.24

Table 3.4 – Calculation of Naphtha’s Vapor Pressure at different

temperature(this is further used for calculation partial pressures)

Sample Calculations at T = 30 oC.

Ptotal = 53.03395 kPa = 0.54078 kg/cm2 Density = 0.69 gm/cm3 Diameter = 2 in = 0.0508 m Length = 10 cm Using Darcy–Weisbach equation,

Where the pressure loss due to friction Δp (Pa) is a function of:


the ratio of the length to diameter of the pipe, L/D;

the density of the fluid, ρ (kg/m3);

the mean velocity of the flow, V (m/s), as defined above;

Darcy Friction Factor; a (dimensionless) coefficient of laminar, or turbulent flow, fD.

fD = 0.026 (calculated from Moody Diagram, taking € = 0.15 mm )

From, above equation the velocity is found out to be,

V = 0.0421687 m/s

Area of the outlet = 0.00203 m2

Therefore, Volumetric flow rate = 0.085 * 10-3 m3/sec

On an average 6 trucks are loaded per day and each loading takes 45 minutes

approximately.

Loss of Naphtha is 0.9639 MT.

Fig 3.3 The Temperature v/s Losses Curve

0.9639

1.5982

1.7462

1.8971

2.05982

y = -0.02x4 + 0.2817x3 - 1.4328x2 + 3.2612x - 1.1262R² = 1

0

0.5

1

1.5

2

2.5

30 35 40 45 50

losess


Chapter - 4

Results and Discussions

Phase – I

Given Data

Heat Rejected/

Absorbed or Power

Produced

Evaporator E-126

Ti= -9 oC = 264 K To= -35 oC = 238 K

Volumetric flow rate = 162.2 m3/hr m= 54 kg/sec

2380.24 kW = 679 tons

Flash Pot V-126

Temperature is constant at -44.3 oC Phase change takes place

λ = 415.85 kJ/kg m = 4.14 kg/sec

1721.94 kW= 491

tons

Table 4.1 –Results of calculations for Phase – I

Hence, total ton of refrigeration is equivalent to (679 + 491) tons.

QL = 1170 tons

The calculation of tons of refrigeration of the Phase- I is being carried by the

summation of the Heat lost/gained by the vessels E-126 and V-126. This done by

the basic analysis of the refrigeration cycle. The calculations are aptly described in

the Chapter - 3.

From the calculations it is evident that the tons of refrigeration is more in the Phase

– I than in the Phase – II. The reason to this that the flash pot is not in function in

Phase – II as the Chiller is just been replaced and it is being operated at a high


efficiency rendering V-126 useless as the heat requirements are met without it.

Phase – II

Given Data

Heat Rejected/

Absorbed or Power

Produced

Compressor 1st Stage

P1= 1.171 kg/cm2=114737.805 Pa P2= 4.3 kg/cm2

V1= 15.4 km3/hr = 4.27 m3/sec (at N.T.P) V1= 3.086 m3/sec (at operating conditons)

568.15 kW = 162 tons

Compressor 2nd Stage

P1= 4.27 kg/cm2=418749.955 Pa P2= 16.2 kg/cm2

V1= 36.3 km3/hr =10.083 m3/sec (at N.T.P) V1= 2.39 m3/sec (at operating conditions)

1807.60 kW = 515 tons

Condenser E-125

Ti=89.9 oC = 363 K To=35 oC = 308 K

Volumetric flow rate = 36.3 km3/hr = 10.083 m3/sec

m= 111.83 kmol/sec

504.97 kW = 144 tons

Evaporator E-126

Ti= -18 oC = 255 K To= -28 oC = 245 K

Volumetric flow rate = 162.2 m3/hr m= 54 kg/sec

2465.06 kW = 703 tons

Flash Pot V-126 Valve LIC-305 is closed

Hence, no there is no flow. -

Table 4.2 –Results of calculations for Phase – II

Hence, total tons of refrigeration is equivalent

QL = 703 tons


W = 677 tons

QH= 144 tons

Losses of Naphtha per day at different temperatures are,

Temperature Losses in MT

30 oC 0.9639 35 oC 1.5982 40 oC 1.7462 45 oC 1.8971 50 oC 2.05982

Table 4.3 –Net Losses of Naphtha in MT at different temperatures

Initial boiling point of the naphtha is 35oC. At the loading gantry some losses arise

as the vapor pressure of components of naphtha is equivalent to their partial

pressure. This kind of vapor losses is uniquely associated with only Naphtha Loading

Gantry, as it is done open to atmosphere and there is absence of any vapor

balancing line to counter the vapor formation and recirculate them. The main

components lost are the low molecular weight hydrocarbons in the Naphtha.

The mole % of pentane and iso-pentane is about 40%, there are some traces of

even some isomers of butane. These hydrocarbons are generally lost in from of

Vapors.

Loading Losses of Naphtha are not continuous in nature and vary widely with

atmospheric conditions. As evident in Table 3.3 the losses are huge in extreme

summers as the atmospheric temperature is as high as 50 oC and minimal in

extreme winters at a temperature of 20 oC. This variation is due to the fact that at

lower temperature less % components of Naphtha reach to the juncture of vapor

formation then compared to higher ones. Thus, influencing the losses.

Loss of Naphtha are severe from Health and Safety issues as the chemical is highly

hazardous and care must be taken to minimize them.


Chapter - 5

Conclusion

The importance of this project lies in gaining the engineering experience and

knowledge which is required in industries and is not taught in class room. Also its

significance lies in the exposure of the engineering responsibilities and ethics.

The calculation of tonnage is provided to E-126 condenser and E-101 chiller by PRU

gives the idea of the working of the any refrigeration system. We found from the

calculation that heat absorbed by propane refrigerant from E-126 is more than that

of absorbed by it from E-101 for phase-I and in phase-II only heat absorbed by E-

126.

Recovery of Naphtha can be done by:

1. We can reduce the vapor loses by reducing the temperature of naphtha

before the loading by the heat exchanger.

2. The time management is another option for the reducing the losses. The

problem is the high temperature in summer but in winter and rain its

favorable. Hence, we pursue loading at the phases when temperature is

low viz. morning and evening.

Though, the methods have their limitations and the question always will be what

is more viable and feasible?


References

1. Perry’s Chemical Engineering Handbook, Seventh Edition.

2. Introduction to Chemical Engineering Thermodynamics, J. M .Smith, H.C.

Ness, M.M. Abbott, Mc Graw Hill Publications.

3. Thermodynamics: A Engineering Approach, Thomas A. Cengel, Micheal A.

Boles, Mc Graw Hill Publications.

4. Unit Operations Of Chemical Engineering , 5th Ed, McCabe and Smith, Mc

Graw Hill Publications.


List of Tables

Table 2.1 General Summary of Product Types and Distillation Range

Table 3.1 – Calulation of Cp from the constants for PHASE - II

Table 3.2 – Calulation of Cp from the constants for PHASE - I

Table 3.3 – Losses in MT per month

Table 3.4 – Calculation of Naphtha’s Vapor Pressure at different

temperature

Table 4.1 –Results of calculations for Phase – I

Table 4.2 –Results of calculations for Phase – II

Table 4.3 –Net Losses of Naphtha in MT at different temperatures


List of Figures

Fig 1.1 Layout of Gas Processing Unit (GPU)

Fig 1.2 Process Flow Diagram TR-12

Fig 2.1 A schematic refrigerator

Fig 2.2 Schematic of Propane Refrigeration Unit

Fig 3.1 LEF Columnn

Fig 3.2 : The Basic Representation Of Chiller

Fig 3.3 The Temperature v/s Losses Curve


List of Photographs

Schematic Of HVJ/GREP/DV Pipeline

Gas Compressor Station

Centralized Pipeline Maint. Base

LPG Phase 1(Train 11)

LPG Phase 2 (Train 12)

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